MediaWiki is a free software wiki package originally written for Wikipedia.
A wiki is a page or collection of Web pages designed to enable any user to contribute or modify content, using a simplified markup language. Wikis are often used to create collaborative websites and to power community websites.
The collaborative encyclopedia Wikipedia is one of the best-known wikis. Wikis are used in business to provide intranets and Knowledge Management systems. MediaWiki is an extremely powerful, scalable software and a feature-rich wiki implementation, that uses PHP to process and display data stored in its MySQL database.